Respiratory hazards abound in livestock barns

Airborne contaminants that can affect worker health include dust particles and gases such as carbon dioxide and ammonia

RED DEER — Agriculture is the fourth most hazardous industry in Canada, but the statistic does not break down specific risks, such as the damaging effects of airborne contaminants in a hog or poultry barn.

“You could be exposed to a myriad of contaminants in your barns,” said Irene Wenger of the University of Alberta’s School of Public Health.

Occupational health research indicates a higher risk of bronchitis among people working in enclosed hog or poultry barns. They have more difficulty with chronic cough and phlegm, wheezing, more headaches, increased chest tightness and shortness of breath.

“You are exposed to a lot of different things in your everyday work and you are probably exposed to contaminants when you are doing your hobbies as well,” she told the Western Poultry Conference, held Feb. 24 in Red Deer.

Dust particles come in many forms and sizes. In poultry barns it arises from shavings on the floor, pollen grains, feathers, dried manure, skin flakes and dust mites.

Inhalable dust is about 100 microns in size, which is the same diameter as a hair root. This is a larger particle, and when people breathe it in, more than 90 percent is filtered out by the nose.

“If you are a mouth breather … you are going to bypass some of that and breathe those contaminants deeper into the lungs” she said.

Thoracic dust is about 10 microns in diameter, about the size of baby powder granule. This dust is not seen and never settles. It can be inhaled deeper into the airways of the lungs.

Respirable dust is four microns in diameter and can be inhaled deep into the lower respiratory tract and enter the gas exchange region of the lungs.

Micro-organisms in the dust can include endotoxins. These are part of the cell wall of gram-negative bacteria and can cause reduced lung function and bronchial restriction, making it difficult to breathe.

People can develop organic dust toxic syndrome with flu-like symptoms, fever, headaches, mucus membrane irritation and muscle pain attributed to the endotoxins.

Barn workers need to wear an N95 respirator, which filters out about 95 percent of the small airborne particles. There are higher levels available, but as the number increases it is harder to draw breath through the respirator.

Gases are also present in barns.

Carbon dioxide is colourless and comes from animal respiration. It builds up with inadequate ventilation. High concentrations of carbon dioxide may not be lethal, but lack of oxygen is the danger.

Carbon monoxide may come from barns with unvented gas heaters and inadequate ventilation.

Ammonia is colourless with a sharp, irritating odour. It is due to inadequate ventilation, little moisture and temperature. Ammonia can go deep into the lungs, travelling on small dust particles.

“You can get burning and lung damage because of the combination of the ammonia and dust,” Wenger said.

Hydrogen sulfide is not found in poultry barn gas, but it can be present in hog and dairy cow barns when manure slurry is agitated.

It is colourless and has a rotten egg smell at low concentrations.

“At 35 parts per million you can’t smell it anymore because your olfactory nerve has now been deadened,” she said.

It is dangerous at 100 p.p.m. and can knock a person down at 500 p.p.m. It is fatal at 1,000 p.p.m.

Noise is another risk in barns.

Fans, pressure washers, leaf blowers or hammering during maintenance can cause noise-induced hearing loss.

“There are a lot of noisy things in your barn and you do not always think about protecting your hearing,” she said.

Guidelines for contaminants and exposure limits can be found at

Noise limits may be found at

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